ranscription factor, BTB-ZF family
A gene called "fruitless" was identified
in fruit flies in the 1970's which influences sexual preference. Males
with the gene mutation are unable to discriminate between the sexes,
engaging both male and female flies in courtship behaviors. Males
with severe mutations in fruitless lose interest in sex altogether. When
confronted with cues that elicit sexual behavior in normal males,
fruitless males fail to follow female flies, play courtship songs
on their wings, or attempt copulation. The fruitless gene
codes for a transcription factor expressed in fruit fly brain cells
that plays a role in turning other genes on and off. Roush, Science,
274:1836, 1996; Ryner et al., Cell, 1079, 1996; Villella et al.,
Genetics, 147:1107-1130, 1997.
Xq28 + [HGL]
A certain DNA marker on the Xq28 region of the
X chromosome was correlated with male homosexuality. Males
in the family who had inherited a X chromosome from their mother
bearing this signpost were more likely to be gay than their male
relatives who had not. Hamer et al., Science, 261:321, 1993. Since
the publication of this work, other groups have been unable to repeat
it, making the "gay" gene controversial, but not dead.
Wickelgren, Science, 284: 571, 1999; Rice et al., Science, 284:665-667,
1999. The original researchers still stick by their data. Hamer,
Science, 285:803, 1999.
arginine vasopressin (AVP) receptor, subtype 1a (V1a-receptor)
[GE]
Arginine vasopressin (AVP) is an amino acid neurotransmitter
involved in many species-typical behaviors, including male social
behaviors, communication, aggression, sexual behavior, and in monogamous
species, pair bonding and parental care. The effects of AVP
are mediated by the V1a-receptor, a member of a family of G-protein
coupled receptors. When AVP is injected into the brain of a
male, monogamous, prairie vole, it displays increased affiliative
behavior to a stimulus female. Injection of AVP into the brain
of a male, polygamous montane vole had no effect. The effect
of AVP appears to be related to its distribution in the brain since
the receptor has the same binding characteristics in each vole type
but has strikingly different patterns of expression in the brain. Transgenic
mice were created which expressed the prairie vole V1a receptor. The
brains of such mice had a similar pattern of expression as the brain
of a prairie vole but different from the montane vole. Like
the prairie vole, injection of AVP into the transgenic mice increased
affiliative behavior. This supports the theory that the species
different distribution of the V1a receptor accounts for the affiliative
response to AVP. Young et al, Nature, 400:766-768, 1999. |